【作者】 王伟；

【导师】 钟铁毅；

【作者基本信息】 北京交通大学 ， 土木工程， 2020， 硕士

【摘要】 随着国民经济发展和路网的延伸,桥梁预制构件和装配式体系的研究、开发和应用越来越受到关注。节段拼装桥墩及其施工技术具有保证施工质量、提高生产效率、降低人力成本、减小施工干扰、节能环保等优点,在公路和市政桥梁工程中得到了越来越多的应用。2019年,随着中国高铁首段装配式一体化桥梁主体工程在京雄城际铁路率先完成,开启了装配式桥墩在铁路工程中应用的序幕。随后,郑济高速铁路、中兰高速铁路、和若铁路及盐城大丰港支线铁路等皆有标段采用预制装配式桥墩施工技术,其中不乏有八度高烈度设防区,但目前存在着抗震性能不明确及设计方法不完善等问题,限制了其在高烈度地震区的应用,为确保该结构体系在高烈度设防区的抗震安全性,亟待针对该体系开展抗震设计理论与试验研究。本文以在建高速铁路项目为背景,选取实际工程中某一代表性预制节段拼装圆端形空心墩为研究对象,通过理论分析和数值计算研究,探讨了设计参数对抗震性能的影响,采用了粘弹性阻尼器对节段拼装桥墩进行抗震性能优化和改进的方案,研究给出了节段拼装空心墩基于位移的抗震设计方法。本文主要工作如下:(1)根据节段拼装桥墩基本组件的受力特点,分析了桥墩在水平力作用下耗能钢筋、预应力筋的应力状态,给出了节段拼装桥墩基于截面分析的抗弯承载力计算方法。归纳了桥墩连接接缝及墩身抗剪计算公式,为防止剪切破坏发生,本文采用包络计算的方式进行验算。本章的研究可为进一步的试验设计和抗震设计理论研究提供支持。(2)设计制作了2个桥墩试验试件,详细描述了耗能钢筋、剪力键、预应力筋等重要部件的施工过程,制定结构加载及测量系统,为进一步的试验研究奠定了基础。(3)基于Mander约束混凝土模型理论,推导建立了适用于圆端形空心墩的约束混凝土本构,给出了采用ABAQUS软件模拟混凝土损伤、无粘结预应力、接触面作用的方法,并进行了验证。建立了节段拼装圆端形空心墩和现浇钢筋混凝土圆端形空心墩实体单元模型,进行了拟静力数值分析,通过滞回特性对比分析了二者的差异。研究了恒载轴压比、初始预应力数值、预应力筋配筋率、预应力筋布置位置、耗能钢筋配筋率、墩身节段数量等主要设计参数对节段拼装圆端形空心墩抗震性能的影响规律。(4)节段拼装桥墩存在耗能能力差的缺陷,提高耗能钢筋配筋率有助于改善这一不足。但研究发现当耗能钢筋率提高至某一数值后,使墩身与承台连接刚度过高,开合能力减弱,摇摆截面转移,耗能能力反而降低。针对该问题,本文研究给出了耗能钢筋配筋率的合理取值。(5)针对本文节段拼装桥墩结构形式及变形特点,采用了桥墩外置粘弹性阻尼器的改进措施。建立了地震力作用下的力学模型,对不同耗能钢筋配筋率的外置阻尼器桥墩进行滞回耗能分析对比。同时,依据抗震规范选取和生成远场地震波、近断层地震波,分别计算了现浇钢筋混凝土圆端形空心墩、节段拼装圆端形空心墩、外置粘弹性阻尼器的节段拼装圆端形空心墩在罕遇地震下的时程响应,对比分析了桥墩墩顶位移、墩底剪力、预应力筋应力等参数;研究了桥墩采用粘弹性阻尼器改进措施的耗能减震效果。(6)本文基于位移的抗震设计思想,提出了节段拼装空心墩抗震设计方法,实现了性能化的抗震设计,所提方法涵盖了以粘弹性阻尼器为减震措施的相关设计步骤,并给出了具体算例,为实际工程设计提供了参考。更多还原

【Abstract】 With the development of the national economy and the extension of the road network,the research,development and application of bridge prefabricated components and fabricated systems have received increasing attention.Segment assembled bridge pier and its construction technology have the advantages of ensuring construction quality,improving production efficiency,reducing labor cost,reducing construction interference,energy saving and environmental protection,etc.,and are increasingly used in highway and municipal bridge engineering.In 2019,with the completion of the first section of China’s high-speed rail prefabricated integrated bridge main project on the Beijing-Xiong’an Intercity Railway,the prelude to the application of prefabricated bridge piers in railway engineering has begun.Subsequently,Zhengzhou-Jinan High-speed Railway,ZhongweiLanzhou High-speed Railway,Hetian-Ruoqiang Railway and Dafeng Port Railway Extension all adopted standard prefabricated bridge pier construction technology,among which there are fortification zones with high intensity of 8 degrees.However,there are problems such as unclear seismic performance and imperfect design methods,which limit its application in high-intensity earthquake areas.In order to ensure the seismic safety of the segment assembled bridge pier structural system in the high-intensity fortification zone,it is urgent to carry out seismic design theory and experimental research for this system.Based on the background of the high-speed railway project under construction,this paper selects a representative prefabricated segment assembled round-end hollow pier in actual engineering as the research object.Through theoretical analysis and numerical calculation research,the influence of design parameters on seismic performance is discussed.Moreover,a scheme to optimize and improve the seismic performance of prefabricated bridge piers using viscoelastic dampers is proposed.And the research gives the displacement-based seismic design method of segment assembled hollow pier.The main work of this paper is as follows:(1)According to the stress characteristics of the basic components of the segment assembled pier,the stress states of the energy dissipation steel bars and prestressed tendons of the pier under the action of horizontal force were analyzed,and the calculation method of flexural bearing capacity of section-assembled bridge piers based on section analysis was given.Meanwhile,summarized the calculation formulas of bridge pier connection cracks and pier body shear resistance.In order to prevent the occurrence of shear failure,this paper used envelope calculation method to check.The research in this chapter can provide support for further experimental design and theoretical research on seismic design.(2)Two test specimens of bridge piers were designed and manufactured,which described the construction process of energy dissipative steel bars,shear keys,prestressed steel bars and other important components in detail,and formulated structures loading and measurement system.Laid the foundation for further experimental research.(3)Based on the theory of Mander’s constrained concrete model,the constitutive of the constrained concrete suitable for the round-end hollow pier was derived,and the method of simulating concrete damage,unbonded prestress and contact surface using ABAQUS software was given.Moreover,the solid element model of segment assembled round end hollow pier and cast-in-situ reinforced concrete round end hollow pier was established,and the pseudo-static numerical analysis was carried out.The difference between the two models was analyzed through the comparison of hysteretic characteristics.At the same time,the influence of main design parameters such as constant load axial compression ratio,initial prestress value,prestressed reinforcement ratio,prestressed reinforcement layout position,reinforcement ratio of energy dissipative steel bars and number of pier sections on the seismic performance of segment assembled round end hollow pier was studied.(4)The segmented assembled pier has the defect of poor energy dissipation capacity.Increasing the energy dissipation reinforcement ratio helps to improve this deficiency.However,the study found that when the energy dissipation reinforcement rate increased to a certain value,the stiffness of the connection between the pier and the bearing cap was too high,the opening and closing capacity was weakened,the swaying section was transferred,and the energy consumption capacity was reduced.In response to this problem,the research in this paper gives a reasonable value for the reinforcement ratio of energy-consuming steel bars.(5)In view of the structural form and deformation characteristics of the assembled pier in this section,the improvement measures of setting viscoelastic damper outside the pier were adopted.The mechanical model under earthquake load was established,and the hysteretic energy dissipation analysis and comparison of external damper piers with different energy dissipation reinforcement ratios were carried out.At the same time,selecting and generating far-field seismic waves and near-fault seismic waves according to seismic specifications.The time-history response analysis of the cast-in-place reinforced concrete round-end hollow pier,the segment-assembled round-end hollow pier,and the externally-assembled round-end hollow pier with external viscoelastic dampers were calculated.In addition,the parameters of bridge pier top displacement,pier bottom shear,prestressed tendon stress and other parameters were compared and analyzed,and the energy dissipation and vibration reduction effects of the viscoelastic damper improvement measures proposed in this paper were studied.(6)Based on the seismic design concept of displacement,this paper proposed a seismic design method for segment assembled hollow piers to achieve a performance-based seismic design.The proposed method covers the relevant design steps with viscoelastic dampers as shock-absorbing measures and gives specific calculation examples.It provides a reference for actual engineering design.更多还原